1. Technical Field
The present invention relates to a chemical analysis apparatus for extracting a specific chemical substance, such as nucleic acid, from a biological sample, such as blood or urine. An extracted chemical substance such as nucleic acid is mixed with a reagent for detection, and the mixture is analyzed. The invention also relates to a genetic diagnostic apparatus equipped with the chemical analysis apparatus.
2. Background Art
As an example of a chemical analysis apparatus for extracting and analyzing a specific chemical substance, such as nucleic acid, from a sample including a plurality of chemical substances, JP Patent Publication (PCT Translation) No. 2001-527220 (WO99/33559) discloses an integrated fluid manipulation cartridge. This device includes a reagent such as a solvent, a washing solution, or an eluent, and a capturing component for capturing nucleic acids. A sample including nucleic acid is injected into the cartridge and mixed with the eluent, and the mixture is passed through the capturing component. Further, the washing solution is passed through the capturing component, and then the eluent is passed through the capturing component. The eluent is brought into contact with a PCR reagent after passing through the capturing component and caused to flow toward a reaction chamber.
As an example of the method of extracting nucleic acids that is employed in the above-mentioned first prior art, JP Patent Publication (PCT Translation) No. 8-501321 (WO95/01359) discloses a method of purifying and separating a nucleic acid mixture by chromatography. In this method, the nucleic acid mixture is adsorbed on a mineral substrate of silica gel, for example, from an aqueous adsorption solution containing a high concentration of salts. The substrate is washed by a washing solution, and nucleic acids are eluted with a solution having a low concentration of salts. The silica gel is fixed inside a hollow cylindrical column, into which a solution of the nucleic acid mixture to be separated is poured and passed through the mineral substrate by suction or centrifugation.
WO00/78455 further discloses a microstructure and a method for examinations based on amplification. The disclosed apparatus, using the nucleic-acid mixture purification and separation method according to the above-mentioned JP Patent Publication (PCT Translation) No. 8-501321 (WO95/01359), passes a DNA mixture through a glass filter as a mineral substrate, and then passes it through a washing solution and an eluent, thereby collecting only DNA. The glass filter is provided on a rotatable structure, and reagents, such as the washing solution and eluent, are stored in individual reagent reservoirs inside the same structure. Each reagent is moved by the centrifugal force created by rotation of the structure, and the reagents are passed through the glass filter by opening a valve provided on a micropath connecting each reagent reservoir and the glass filter.
JP Patent Publication (PCT Application) No. 2001-502793 (WO98/13684) discloses an apparatus and method for chemical analysis. The apparatus comprises a disc-shaped member which has a chamber, paths, a reservoir, and analysis cells. A blood sample is introduced into the centrifugal chamber and centrifuged to separate blood cells from serum. Only the serum is caused to flow into a reaction chamber having beads, the surface of which has been coated with a reagent. Then, a washing solution flows into the reaction chamber, to which an eluting solution further flows. Thereafter, the eluting solution is moved from the reaction chamber to the analysis cells.
In the first prior art, namely that regarding the integrated fluid manipulation cartridge according to JP Patent Publication (PCT Translation) No. 2001-527220 (WO99/33559), when the individual reagents are delivered by pump, the valve or the like provided on the micropath connecting each reagent chamber and the capturing component is opened, thereby passing the reagent through the capturing component. Of the reagents that have passed through the capturing assembly, the washing solution is caused to flow to a waste chamber while the eluent is caused to flow to the reaction chamber by controlling the valve or the like provided on the path between the capturing component and each chamber. When a plurality of reagents are delivered by pump, the reagents remain on the walls of the paths, particularly when there is an obstacle such as a valve. Once such liquids are left, they never move, and it is possible for one reagent to cause contamination at the connecting point. Further, when the washing solution and the elution fluid that have passed through the capturing component are caused to flow to separate chambers by switching the valve or the like, the washing solution that has first flowed to the waste chamber can contaminate the path upstream of the value or the like used for switching to the reaction chamber, possibly resulting in the washing solution mixing with the elution liquid.
According to the second prior art, namely that regarding the purification and separation method disclosed in JP Patent Publication (PCT Translation) No. 8-501321 (WO95/01359), the nucleic acid mixture is introduced into the hollow cylindrical column in which silica gel is fixed. After passing the nucleic acid mixture through the silica gel by centrifugal force, a plurality of reagents are passed through, thereby collecting only nucleic acids. This publication, however, does not disclose the method of introducing the individual reagents into the hollow column or the method of collecting the washing solution and the elution fluid that have been passed through the silica gel.
According to the third prior art, namely that regarding the structure disclosed in WO00/78455, the individual reagents pass through the glass filter when moved by centrifugal force as the valve provided on a micropath connecting each reagent reservoir and the glass filter is opened. While the valve is made of wax that melts when heated, there is a possibility that a reagent that has passed through could remain at the valve and contaminate the collected DNA. Specifically, the DNA mixture or the washing solution may remain in the valve, and it is possible for the remaining DNA mixture or the washing solution to flow into the glass filter as the elution liquid is passed through the glass filter by centrifugal force.
According to the fourth prior art, namely that regarding the apparatus known from JP Patent Publication (PCT Translation) No. 2001-502793 (WO98/13684), when the blood serum is separated, the disc-shaped member revolves around a central axis outside of the disc-shaped member (revolution), and when the serum is guided to the reaction chamber, the disc-shaped member rotates about a central axis within itself (rotation). Thus, individual rotating mechanisms are required for the revolution and the rotation, which complicates the apparatus. Further, when the washing solution and the elution liquid are guided to the reaction chamber, a piston in a cylinder provided inside the disc-shaped member is driven, which further complicates the apparatus.